Circuit board having heat-dissipation block and method of manufacturing the same

ABSTRACT

A circuit board includes an open substrate and a heat dissipation block. The open substrate includes a substrate body, an opening and at least one first fixing portion and at least one second fixing portion. The substrate body has a top surface and a bottom surface. The opening is in the substrate body and has a first sidewall and a second sidewall opposite to the first sidewall. The first fixing portion and the second fixing portion extends from the substrate body toward the opening, in which the first fixing portion and the second fixing portion are respectively protruded from the first sidewall and the second sidewall. The heat dissipation block is directly clamped between the first fixing portion and the second fixing portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation-in-part of U.S. application Ser. No.16/283,849, filed on Feb. 25, 2019, which claims priority to TaiwanApplication Serial Number 107147514, filed Dec. 27, 2018, the entiretyof which is incorporated by reference herein.

BACKGROUND Field of Invention

The present disclosure relates to a circuit board having a heatdissipation block and a method of manufacturing the same.

Description of Related Art

Electronic components (e.g., chips) in a wiring structure generate heatduring operation, so a heat dissipation block is usually disposed toconduct the heat generated by the electronic components to outside ofthe wiring structure. Copper is currently and commonly used as the heatdissipation block due to its ductility and good processability. However,the copper heat dissipation block has a high coefficient of thermalexpansion (CTE), which is more susceptible to expansion and deformationwhen heated, and the difference in degree of thermal expansion betweenthe components may cause a circuit board to warp.

In addition, when the heat dissipation block in the circuit board ismade of a material having a low coefficient of thermal expansion and lowductility (e.g., silicon carbide), a method of manufacturing the circuitboard having the heat dissipation block is to initially fix the heatdissipation block using an adhesive layer, and then to fill a resinmaterial to fix the heat dissipation block. However, in this method,finally, the adhesive layer needs to be peeled off, and the heatdissipation block is easily displaced during the peeling process.

Therefore, there is a need for a novel method of manufacturing a circuitboard having a heat dissipation block to solve the above problems.

SUMMARY

According to various embodiments of the present disclosure, circuitboard is provided. The circuit board includes an open substrate and aheat dissipation block. The open substrate includes a substrate body, anopening and at least one first fixing portion and at least one secondfixing portion. The substrate body has a top surface and a bottomsurface. The opening is in the substrate body and has a first sidewalland a second sidewall opposite to the first sidewall. The first fixingportion and the second fixing portion extends from the substrate bodytoward the opening, in which the first fixing portion and the secondfixing portion are respectively protruded from the first sidewall andthe second sidewall. The heat dissipation block is directly clampedbetween the first fixing portion and the second fixing portion, in whichthe heat dissipation block includes ceramic or a composite material.

According to some embodiments of the present disclosure, an aperture ison the first fixing portion and the second fixing portion and betweenthe open substrate and a top portion of the heat dissipation block, andthe first fixing portion and the second fixing portion respectively havea height that is smaller than a thickness of the open substrate.

According to some embodiments of the present disclosure, a bottomportion of the heat dissipation block is tight contact with the firstfixing portion and the second fixing portion.

According to some embodiments of the present disclosure, the aperturehas a depth of about 0.2-0.5 of a thickness of the substrate body.

According to some embodiments of the present disclosure, the top surfaceof the substrate body is level with a top surface of the heatdissipation block.

According to some embodiments of the present disclosure, the firstfixing portion has a first width protruding from the first sidewall, andthe second fixing portion has a second width protruding from the secondsidewall, in which the first width and the second width are in a rangeof from about 0.05 mm to about 0.5 mm.

According to some embodiments of the present disclosure, the firstfixing portion has at least two first protrusions in contact with theheat dissipation block and at least one first recess located between thefirst protrusions and the heat dissipation block, and the second fixingportion has at least two second protrusions in contact with the heatdissipation block and at least one second recess located between thesecond protrusions and the heat dissipation block.

According to some embodiments of the present disclosure, the opensubstrate further includes at least one third fixing portion and atleast one fourth fixing portion extending from the substrate body towardthe opening, and the heat dissipation block is clamped between the thirdfixing portion and the fourth fixing portion.

According to some embodiments of the present disclosure, the opening hasround corners at both ends of the first sidewall and the secondsidewall.

According to some embodiments of the present disclosure, the heatdissipation block is selected from one of the group consisting ofaluminum silicon carbide (AISiC), tungsten copper alloy (CuW), tungstenmolybdenum alloy (CuMo), silicon carbide (SiC), silicon nitride (AlN),beryllia, chemical vapor deposition diamond (CVD diamond), diamondpowder-doped copper, diamond powder-doped aluminum, carbon-basednano-aluminum composite material (CarbAl-N) and carbon-basednano-aluminum composite material (CarbAl-G).

According to various embodiments of the present disclosure, a method ofmanufacturing a circuit board is provided. The method includes formingan open substrate, in which the open substrate includes a substrate bodyhaving a top surface and a bottom surface; an opening in the substratebody, in which the opening has a first sidewall and a second sidewallopposite to the first sidewall; and at least one first fixing portionand at least one second fixing portion extending from the substrate bodytoward the opening, in which the first fixing portion and the secondfixing portion are respectively protruded from the first sidewall andthe second sidewall. The heat dissipation block is then inserted in theopening to clamp the heat dissipation block between the first fixingportion and the second fixing portion, in which the heat dissipationblock includes the heat dissipation block comprises a ceramic or acomposite material.

According to some embodiments of the present disclosure, the methodfurther includes recessing the first fixing portion and the secondfixing portion to form an cavity; and placing a heat dissipation blockin the cavity.

According to some embodiments of the present disclosure, the cavity hasa width of about 1.03-1.1 of a length of the heat dissipation block.

According to some embodiments of the present disclosure, the cavity hasa depth of about 0.2-0.5 of the thickness of the substrate body.

According to some embodiments of the present disclosure, the heatdissipation block is supported by the first fixing portion and thesecond fixing portion when placing the heat dissipation block in thecavity.

According to some embodiments of the present disclosure, the heatdissipation block has a length that is greater than a distance betweenthe first fixing portion and the second fixing portion.

According to some embodiments of the present disclosure, a top surfaceof the heat dissipation block is protruded from the top surface of thesubstrate body when placing the heat dissipation block in the cavity.

According to some embodiments of the present disclosure, inserting theheat dissipation block in the opening comprises pressing from a topsurface of heat dissipation block to squeeze the heat dissipation blockinto the opening between the first fixing portion and the second fixingportion.

According to some embodiments of the present disclosure, the opensubstrate further includes at least one third fixing portion and atleast one fourth fixing portion extending from the substrate body towardthe opening, and the heat dissipation block is clamped between the thirdfixing portion and the fourth fixing portion.

According to some embodiments of the present disclosure, the heatdissipation block is selected from one of the group consisting ofaluminum silicon carbide (AISiC), tungsten copper alloy (CuW), tungstenmolybdenum alloy (CuMo), silicon carbide (SiC), silicon nitride (AlN),beryllia, chemical vapor deposition diamond (CVD diamond), diamondpowder-doped copper, diamond powder-doped aluminum, carbon-basednano-aluminum composite material (CarbAl-N) and carbon-basednano-aluminum composite material (CarbAl-G).

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the present disclosure will be fully understood fromthe following detailed description when reading the accompanyingdrawings. It is worth noting that various features are not drawn toscale in accordance with standard practice in the industry. In fact,dimensions of the various features may be arbitrarily increased ordecreased for clarity of discussion.

FIG. 1 is a flow chart of a method of manufacturing a circuit boardhaving a heat dissipation block according to various embodiments of thepresent disclosure.

FIGS. 2-8 are top views of a manufacturing method at various stagesaccording to some embodiments of the present disclosure.

FIG. 9 is a top view of a circuit board having a heat dissipation blockaccording to some embodiments of the present disclosure.

FIG. 10 is a cross-sectional view of the circuit board having the heatdissipation block taken along line A-A of FIG. 9.

FIG. 11 is a cross-sectional view of a circuit board having a heatdissipation block according to some embodiments of the presentdisclosure.

FIG. 12 is a flow chart of a method of manufacturing a circuit boardhaving a heat dissipation block according to various embodiments of thepresent disclosure.

FIG. 13 is a top view of a manufacturing method at various stagesaccording to some embodiments of the present disclosure.

FIG. 14 is a cross-sectional view of the circuit board taken along lineA-A′ of FIG. 13.

FIG. 15 is a cross-sectional view of the circuit board taken along lineB-B′ of FIG. 13.

FIG. 16 is a top view of a manufacturing method at various stagesaccording to some embodiments of the present disclosure.

FIG. 17 is a cross-sectional view of the circuit board having the heatdissipation block taken along line A-A′ of FIG. 16.

FIG. 18 is a cross-sectional view of the circuit board having the heatdissipation block taken along line B-B′ of FIG. 16.

FIG. 19 is a top view of a manufacturing method at various stagesaccording to some embodiments of the present disclosure.

FIG. 20 is a cross-sectional view of a manufacturing method taken alongline A-A′ of FIG. 16.

FIG. 21 is a cross-sectional view of a manufacturing method taken alongline B-B′ of FIG. 16.

FIG. 22 is a top view of a manufacturing method at various stagesaccording to some embodiments of the present disclosure.

FIG. 23 is a cross-sectional view of the circuit board having the heatdissipation block taken along line A-A′ of FIG. 22.

FIG. 24 cross is a cross-sectional view of the circuit board having theheat dissipation block taken along line B-B′ of FIG. 22.

FIG. 25 is a cross-sectional view of the circuit board having the heatdissipation block.

DETAILED DESCRIPTION

The drawings disclose a plurality of embodiments of the presentdisclosure below. For the sake of clarity, many practical details willbe explained in the following description. However, it should beunderstood that these practical details are not intended to limit thepresent disclosure. That is, in some embodiments of the presentdisclosure, these practical details are not necessary. Moreover, for thesake of simplicity of the drawings, some conventional structures andelements will be illustrated in a simplified schematic manner in thedrawings.

In the description, spatially relative terms, such as “beneath,”“below,” “over,” “on,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as shown in the figures. The true meaning ofthe spatially relative terms includes other orientations. For example,when the figure is flipped up and down by 180 degrees, the relationshipbetween one component and another component may change from “beneath” or“below,” to “over” or “on.” In addition, the spatially relativedescriptions used herein should be interpreted the same.

Although a series of operations or steps are described below toillustrate the methods disclosed herein, the order of the operations orsteps is not to be construed as limiting. For example, certainoperations or steps may be performed in a different order and/orconcurrently with other steps. In addition, not all illustratedoperations, steps and/or features are required to implement embodimentsof the present disclosure. Moreover, each of the operations or stepsdescribed herein can include a number of sub-steps or actions.

FIG. 1 is a flow chart of a method 10 of manufacturing a circuit boardhaving a heat dissipation block according to various embodiments of thepresent disclosure. As shown in FIG. 1, the method 10 includesoperations 12 and 14. FIGS. 2-8 are top views of a manufacturing methodat various stages according to some embodiments of the presentdisclosure.

Referring to FIGS. 1 and 2, in the operation 12 of the method 10, anopening 300 is formed through a substrate 100 to form an open substrate200, in which the opening 300 has a first sidewall 310 and a secondsidewall 320 opposite to each other. The open substrate 200 includes asubstrate body 210 surrounding the opening 300, at least one firstfixing portion 312 extending from the substrate body 210 toward theopening 300 and protruding from the first sidewall 310, and at least onesecond fixing portion 322 extending from the substrate body 210 towardthe opening 300 and protruding from the second sidewall 320. In variousembodiments, the substrate 100 includes an insulating plate, a metalplate, or a wiring board, but is not limited thereto. In someembodiments, the substrate 100 may be a multi-layered circuit board. Insome embodiments, the process of forming the opening 300 may includedrilling, laser, routing, punching, or a combination thereof, but is notlimited thereto. In some embodiments, the opening 300 may be directlyformed using the punching process. In some embodiments, four corners ofthe opening 300 have an arc-shaped profile recessed toward the substratebody 210, as shown in FIG. 2.

In some embodiments, the first fixing portion 312 has a first width W1protruding from the first sidewall 310, and the second fixing portion322 has a second width W2 protruding from the second sidewall 320, andthe first width W1 and the second width W2 are in a range of from about0.05 mm to about 0.5 mm. The protruding first fixing portion 312 and thesecond fixing portion 322 may be used to fix the heat dissipation blockdisposed in the opening in subsequent processes.

In some embodiments, the opening 300 further has a third sidewall 330and a fourth sidewall 340 opposite to each other, and the third sidewall330 and the fourth sidewall 340 are connected to the first sidewall 310and the second sidewall 320. It should be noted that although the firstfixing portion 312 and the second fixing portion 322 respectivelyprotrude from the longer first sidewall 310 and the second sidewall 320of the opening 300, the present disclosure is not limited thereto. Thefirst fixing portion 312 and the second fixing portion 322 may bedisposed at the shorter third sidewall 330 and the fourth sidewall 340of the opening 300, respectively.

FIGS. 3-7 are top views of open substrates 201, 202, 203, 204, and 205according to other embodiments of the present disclosure. Firstly,referring to FIG. 3, the difference between the open substrate 201 andthe open substrate 200 is that the first fixing portion 312 a of theopen substrate 201 has at least two first protrusions 316 and at leastone first recess 314 located between the first protrusions 316, and thesecond fixing portion 322 a has at least two second protrusions 326 andat least one second recess 324 located between the second protrusions326. In some embodiments, each of the first protrusions 316 may bealigned with one of the second protrusions 326 to stably fix the heatdissipation block in subsequent processes. In some embodiments, thefirst recess 314 and the second recess 324 may be formed using adrilling process. In more detail, in some embodiments, the first fixingportion 312 and the second fixing portion 322 shown in FIG. 2 may berespectively drilled to form the first fixing portion 312 a and thesecond fixing portion 322 a shown in FIG. 3.

Referring to FIG. 4, the difference between the open substrate 202 andthe open substrate 201 is that the open substrate 202 further has atleast one third fixing portion 332 and at least one fourth fixingportion 342. The third fixing portion 332 extends from the substratebody 210 of the open substrate 202 toward the opening 302 and protrudesfrom the third sidewall 330. The fourth fixing portion 342 extends fromthe substrate body 210 of the open substrate 202 toward the opening 302and protrudes from the fourth sidewall 340. In some embodiments, thethird fixing portion 332 has a third width W3 protruding from the thirdsidewall 330, and the fourth fixing portion 342 has a fourth width W4protruding from the fourth sidewall 340, and the third width W3 and thefourth width W4 are in a range of from about 0.05 mm to about 0.5 mm. Insome embodiments, the third width W3 and the fourth width W4 may be thesame as the first width W1 and the second width W2. In otherembodiments, the third width W3 and the fourth width W4 may be differentfrom the first width W1 and the second width W2.

Referring to FIG. 5, the difference between the open substrate 203 andthe open substrate 202 is that the third fixing portion 332 a of theopen substrate 203 has at least two third protrusions 336 and at leastone third recess 334 located between the third protrusions 336, and thefourth fixing portion 342 a has at least two fourth protrusions 346 andat least one fourth recess 344 located between the fourth protrusions346. In some embodiments, the third protrusion 336 has a third width W3protruding from the third sidewall 330, and the fourth protrusion 346has a fourth width W4 protruding from the fourth sidewall 340, and thethird width W3 and the fourth width W4 are in a range of from about 0.05mm to about 0.5 mm. In some embodiments, the third width W3 and thefourth width W4 may be the same as the first width W1 and the secondwidth W2. In other embodiments, the third width W3 and the fourth widthW4 may be different from the first width W1 and the second width W2. Thethird protrusion 336 and the fourth protrusion 346 may be used to fixthe heat dissipation block disposed in the opening together with thefirst protrusions 316 and the second protrusions 326 in subsequentprocesses. In some embodiments, each of the first protrusions 316 may bealigned with one of the second protrusions 326, and each of the thirdprotrusions 336 may be aligned with one of the fourth protrusions 346.In some embodiments, there is a distance D2 between the first fixingportion 312 a and the second fixing portion 322 a, and there is adistance D1 between the third fixing portion 332 a and the fourth fixingportion 342 a. In some embodiments, the distance D1 and the distance D2may be the same. In other embodiments, the distance D1 and the distanceD2 may be different. The distance D1 and the distance D2 may be selectedaccording to the size of the heat dissipation block to be disposed.

Referring to FIG. 6, the open substrate 204 has a plurality of firstfixing portions 312 protruding from the first sidewall 310 of theopening 304, and a plurality of second fixing portions 322 protrudingfrom the second sidewall 320 of the opening 304. In some embodiments,each of the first fixing portions 312 may be aligned with one of thesecond fixing portions 322, and the position of the third fixing portion332 can correspond to that of the fourth fixing portion 342. In someembodiments, the width W1 of the first fixing portion 312 and the widthW2 of the second fixing portion 322 in the open substrate 204 may be thesame as the widths W1 and W2 in the open substrate 200, respectively,and the width W3 of third fixing portion 332 and the width W4 of thefourth fixing portion 342 may be the same as the widths W3 and W4 of theopen substrate 202, respectively, and are not described herein again.

Referring to FIG. 7, the difference between the open substrate 205 andthe open substrate 203 is that the open substrate 205 has a plurality offirst fixing portions 312 a protruding from the first sidewall 310 ofthe opening 305, and a plurality of second fixing portions 322 aprotruding from the second sidewall 320 of the opening 305. In someembodiments, each of the first fixing portions 312 a may be aligned withone of the second fixing portions 322 a, and the position of the thirdfixing portion 332 a may correspond to that of the fourth fixing portion342 a. It should be noted that the number and arrangement of the firstfixing portions 312, 312 a, the second fixing portions 322, 322 a, thethird fixing portions 332, 332 a, and the fourth fixing portions 342,342 a shown in FIGS. 2-7 are only examples, when the size of the openingis larger, more fixing portions may be arranged to stably fix the heatdissipation block in the opening.

Subsequent steps of the method 10 will be described below by taking theopen substrate 203 shown in FIG. 5 as an example.

Referring to FIGS. 1 and 8, in the operation 14 of the method 10, theheat dissipation block 400 is clamped between the first fixing portion312 a and the second fixing portion 322 a to fix the heat dissipationblock 400 in the opening 303, such that the circuit board 1000 havingthe heat dissipation block is formed. In some embodiments, the firstprotrusion 316 of the first fixing portion 312 a and the secondprotrusion 326 of the second fixing portion 322 a are in contact withand fix the heat dissipation block 400. The first recess 314 may belocated between the two first protrusions 316 and the heat dissipationblock 400, and the second recess 324 may be located between the twosecond protrusions 326 and the heat dissipation block 400. As shown inFIG. 8, in some embodiments, when the heat dissipation block 400 isclamped between the first fixing portion 312 a and the second fixingportion 322 a, a first gap 350 is formed between the heat dissipationblock 400 and the first sidewall 310 of the opening 303, and a secondgap 360 is formed between the heat dissipation block 400 and the secondsidewall 320 of the opening 303.

In various embodiments, the heat dissipation block 400 includes aceramic or composite material. In some embodiments, the heat dissipationblock 400 is selected from one of the group consisting of aluminumsilicon carbide (AISiC), tungsten copper alloy (CuW), tungstenmolybdenum alloy (CuMo), silicon carbide (SiC), silicon nitride (AlN),beryllia, chemical vapor deposition diamond (CVD diamond), diamondpowder-doped copper, diamond powder-doped aluminum, carbon-basednano-aluminum composite material (CarbAl-N) and carbon-basednano-aluminum composite material (CarbAl-G). In some embodiments, CuWincludes 10-20% copper (Cu). In some embodiments, CuMo includes 15-20%molybdenum (Mo). In some embodiments, the heat dissipation block 400includes aluminum nitride, aluminum carbide, aluminum silicon carbide,or a combination thereof, but is not limited thereto. The heatdissipation block 400 may be other materials having a low coefficient ofthermal expansion (e.g., less than 10 ppm/K) and low ductility. In someembodiments, the heat dissipation block 400 may have a metal layer (notshown in FIG. 8) formed using a sputtering and/or plating process on itsupper and lower surfaces. The working heat source generated by theelectronic components on the circuit board may be transmitted to outsideof the circuit board through heat conduction characteristics of the heatdissipation block 400 to maintain working performance of the electroniccomponents and maintain their life. In some embodiments, the heatdissipation block 400 is rectangular-shaped. In some embodiments, theheat dissipation block 400 has a length L2 slightly larger than thedistance D2 between the first fixing portion 312 a and the second fixingportion 322 a (shown in FIG. 5). The heat dissipation block 400 may befixed in the opening 303 by the length L2 of the heat dissipation block400 being slightly larger than the distance D2.

In other embodiments, the heat dissipation block 400 may also be clampedbetween the third fixing portion 332 a and the fourth fixing portion 342a. As shown in FIG. 8, the third protrusions 336 of the third fixingportion 332 a and the fourth protrusions 346 of the fourth fixingportion 342 a are in contact with and fix the heat dissipation block400. The third recess 334 is located between the two third protrusions336 and the heat dissipation block 400, and the fourth recess 344 islocated between the two fourth protrusions 346 and the heat dissipationblock 400. In some embodiments, the heat dissipation block 400 has alength L1 slightly larger than the distance D1 between the third fixingportion 332 a and the fourth fixing portion 342 a (shown in FIG. 5). Theheat dissipation block 400 may be fixed in the opening 303 by the lengthL1 of the heat dissipation block 400 being slightly larger than thedistance D1.

In one embodiment, after the operation 14 is completed, the method 10may include other operations or steps, as shown in FIGS. 9-10. Firstly,referring to FIG. 9, which is a top view of a process stage after theoperation 14 according to some embodiments of the present disclosure. Insome embodiments, the method 10 further includes filling a resinmaterial 500 in the first gap 350, the second gap 360, the first recess314, and the second recess 324. In other embodiments, the method 10further includes filling the resin material 500 in the third recess 334and the fourth recess 344. As shown in FIG. 9, after the operation 14,all of the gaps between the heat dissipation block 400 and the opensubstrate 203 may be filled with the resin material 500, so that theheat dissipation block 400 is fixed in the opening 303 to facilitatesubsequent processes performed on the circuit board 2000.

Referring to FIG. 10, which is a cross-sectional view taken along lineA-A of FIG. 9. In some embodiments, the circuit board 2000 may be amulti-layered circuit board. For example, the substrate 100 of thecircuit board 2000 includes a core plate 101, a first circuit layer 110,a second circuit layer 120, a first dielectric layer 112, a seconddielectric layer 122, a first conductive layer 114, and a secondconductive layer 124. It should be understood that the structure of thesubstrate 100 is not limited to that shown in FIG. 10, and the substrate100 may be any circuit board having a multilayered structure.

In another embodiment, after the operation 14 is completed, the method10 further includes forming a third dielectric layer 610 and a fourthdielectric layer 620 over a top surface S1 and a bottom surface S2 ofthe substrate 100, respectively, forming a third conductive layer 710over the third dielectric layer 610, and forming a fourth conductivelayer 720 beneath the fourth dielectric layer 620, as shown in FIG. 11.FIG. 11 is a cross-sectional view of a process stage after the operation14 according to other embodiments of the present disclosure. In someembodiments, the third dielectric layer 610 and the fourth dielectriclayer 620 may be prepregs or other dielectric materials having fluidity.As shown in FIG. 11, the third dielectric layer 610 and the fourthdielectric layer 620 may be filled in the first recess 314 and thesecond recess 324. In some embodiments, the third dielectric layer 610and the fourth dielectric layer 620 may also fill all of the gapsbetween the heat dissipation block 400 and the open substrate 203 shownin FIG. 8, such as the first gap. 350, the second gap 360, the thirdrecess 334, and the fourth recess 344. In some embodiments, the thirdconductive layer 710 and the fourth conductive layer 720 may be copperfoils.

FIG. 12 is a flow chart of a method 20 of manufacturing a circuit boardhaving a heat dissipation block according to various embodiments of thepresent disclosure. As shown in FIG. 12, the method 20 includesoperations 22, 24 and 26. FIGS. 13-25 are respectively top views andcross-sectional views of a manufacturing method at various stagesaccording to some embodiments of the present disclosure. It is notedthat the method depicted in FIG. 12 is merely an example, and is notintended to limit the present invention. Accordingly, additionaloperations may be performed before, during, and/or after the methoddepicted in FIG. 12, and some other operations may only be brieflydescribed herein.

Reference is made to FIG. 12 and FIG. 13. In the operation 22 of FIG.12, an open substrate 203′ is formed. As shown in FIG. 13, the opensubstrate 203′ includes a substrate body 210, an opening 303′, at leastone first fixing portion 312 a′ and at least one second fixing portion322 a′. The top view of the open substrate 203′ shown in FIG. 13 is sameas the top view of the open substrate 203 shown in FIG. 5. However, thestructure of the open substrate 203′ is different from that of the opensubstrate 203 shown in FIG. 5, and the difference is describedhereinafter.

FIG. 14 and FIG. 15 are respectively cross-sectional views of the opensubstrate 203′ taken along line A-A′ and line B-B′ of FIG. 13. As shownin FIGS. 14-15, the substrate body 210 has a top surface S1 and a bottomsurface S2. In some embodiments, substrate body 210 includes aninsulating plate, a metal plate, or a wiring board, but is not limitedthereto.

Reference is made to FIGS. 13-15. The opening 303′ has a first sidewall310, a second sidewall 320 opposite to the first sidewall 310, and acavity C1 therein. The difference between the opening 303′ shown in FIG.13 and the opening 330 shown in FIG. 5 is that the opening 303′ furtherincludes the cavity C1 recessed from the top surface S1 of the opensubstrate 203′. In some embodiments, the process of forming the opening303′ may include drilling, laser, routing, punching, or a combinationthereof, but is not limited thereto. In some embodiments, the opening303′ may be directly formed using the punching process.

In other embodiments, the formation of the opening 303′ includes formingthe opening 303 shown in FIG. 5 penetrating the substrate body 210, inwhich the opening 303 may have a vertical contour in cross-sectionalview. The cavity C1 is then formed in the opening 303 by recessing thefixing portions (e.g., the first fixing portion 312 a, the second fixingportion 322 a, the third fixing portion 332 a and the fourth fixingportion 342 a shown in FIG. 5), thereby forming the opening 303′. Asshown in FIG. 15, the cavity C1 communicates with the opening 303′, andthe cavity C1 has a width W5 that is wider than a distance D2 betweenthe first fixing portion 312 a′ and the second fixing portion 322 a′.Therefore, the opening 303′ has a staircase contour in thecross-sectional view. In some embodiments, the cavity C1 may be formedin other openings by recessing the fixing portions shown in FIGS. 2-4and FIGS. 6-7.

In some embodiments, a depth H1 of the cavity C1 is of about 0.2-0.5 ofa thickness H3 of the substrate body 210. That is, the depth H1 of thecavity C1 may be smaller than or equal to a height H2 of the firstfixing portion 312 a′ and the second fixing portion 322 a′. It is notedthat the cavity C1 shown in FIG. 15 is merely an example, the depth H1of the cavity C1 can be adjusted depending on the thickness H3 ofsubstrate body 210 and the thickness of the dissipation block to beplaced in the opening 303′.

Referring back to FIG. 13. In some embodiments, four corners of theopening 303′ have an arc-shaped profile recessed toward the substratebody 210. In some examples, the opening 303′ has round corners at bothends of the first sidewall 310 and the second sidewall 320. In someembodiments, the opening 303′ further has a third sidewall 330 and afourth sidewall 340 opposite to each other, and the third sidewall 330and the fourth sidewall 340 are connected to the first sidewall 310 andthe second sidewall 320.

The first fixing portion 312 a′ and the second fixing portion 322 a′extends from the substrate body 210 toward the opening 303′. The firstfixing portion 312 a′ and the second fixing portion 322 a′ arerespectively protruded from the first sidewall 310 and the secondsidewall 320. The protruding first fixing portion 312 a′ and the secondfixing portion 322 a′ may be used to fix a heat dissipation block insubsequent processes. The first fixing portion 312 a′ has a first widthW1 protruding from the first sidewall 310, and the second fixing portion322 a′ has a second width W2 protruding from the second sidewall 320. Insome embodiments, the first width W1 and the second width W2 are in arange of from about 0.05 mm to about 0.5 mm.

In some embodiments, the first fixing portion 312 a′ has at least twofirst protrusions 316′ and at least one first recess 314′ locatedbetween the first protrusions 316′, and the second fixing portion 322 a′has at least two second protrusions 326′ and at least one second recess324′ located between the second protrusions 326′. In some embodiments,each of the first protrusions 316′ may be aligned with one of the secondprotrusions 326′ to stably fix the heat dissipation block in subsequentprocesses. In some embodiments, the first recess 314′ and the secondrecess 324′ may be formed using a drilling process. It should be notedthat although the first fixing portion 312 a′ and the second fixingportion 322 a′ respectively protrude from the longer first sidewall 310and the second sidewall 320 of the opening 303′, the present disclosureis not limited thereto. The first fixing portion 312 a′ and the secondfixing portion 322 a′ may be disposed at the shorter third sidewall 330and the fourth sidewall 340 of the opening 303′, respectively.

As shown in FIG. 15, the first fixing portion 312 a′ and the secondfixing portion 322 a′ are disposed under the cavity C1. In specific, thefirst fixing portion 312 a′ and the second fixing portion 322 a′ shownin FIG. 13 and FIG. 15 are thinned compared with the first fixingportion 312 a and the second fixing portion 322 a shown in FIG. 5.Therefore, the height H2 of the first fixing portion 312 a′ and thesecond fixing portion 322 a′ are respectively smaller than the thicknessH3 of the substrate body 210.

Referring back to FIG. 13. In some embodiments, the open substrate 203′further includes at least one third fixing portion 332 a′ and at leastone fourth fixing portion 342 a′. The third fixing portion 332 a′extends from the substrate body 210 of the open substrate 203′ towardthe opening 303′ and protrudes from the third sidewall 330. The fourthfixing portion 342 a′ extends from the substrate body 210 of the opensubstrate 203′ 202 toward the opening 303′ and protrudes from the fourthsidewall 340. In some embodiments, the third fixing portion 332 a′ has athird width W3 protruding from the third sidewall 330, and the fourthfixing portion 342 a′ has a fourth width W4 protruding from the fourthsidewall 340, and the third width W3 and the fourth width W4 are in arange of from about 0.05 mm to about 0.5 mm. In some embodiments, thethird width W3 and the fourth width W4 may be the same as the firstwidth W1 and the second width W2. In other embodiments, the third widthW3 and the fourth width W4 may be different from the first width W1 andthe second width W2. In some embodiments, the third fixing portion 332a′ and the fourth fixing portion 342 a′ respectively have a height thatis substantially equal to the height H2 of the first fixing portion 312a′ and the second fixing portion 322 a′.

In some embodiments, the third fixing portion 332 a′ has at least twothird protrusions 336′ and at least one third recess 334′ locatedbetween the third protrusions 336′, and the fourth fixing portion 342 a′has at least two fourth protrusions 346′ and at least one fourth recess344′ located between the fourth protrusions 346′. The third protrusion336′ and the fourth protrusion 346′ may be used to fix the heatdissipation block disposed in the opening 303′ together with the firstprotrusions 316′ and the second protrusions 326′ in subsequentprocesses. In some embodiments, each of the third protrusions 336′ maybe aligned with one of the fourth protrusions 346′. In some embodiments,a distance D2 between the first fixing portion 312 a′ and the secondfixing portion 322 a′ is same as a distance D1 between the third fixingportion 332 a′ and the fourth fixing portion 342 a′. In otherembodiments, the distance D1 is different from the distance D2. Thedistance D1 and the distance D2 may be selected according to the size ofthe heat dissipation block to be accommodated in the opening 303′.

Subsequent steps of the method 20 will be described below by taking theopen substrate 203′ shown in FIGS. 13-15 as an example.

Reference is made to FIGS. 16-18. In the operation 24 of FIG. 12, a heatdissipation block 400 is placed in the cavity C1. FIG. 17 and FIG. 18are respectively cross-sectional views taken along line A-A′ and lineB-B′ of FIG. 16. As shown in FIG. 18, the heat dissipation block 400 isplaced on the first fixing portion 312 a′ and the second fixing portion322 a′. Specifically, the heat dissipation block 400 may be temporarysupported by the fixing portions (e.g. the first fixing portion 312 a′and the second fixing portion 322 a′). The heat dissipation block 400has a top surface S401, a bottom surface S402 and a side surface S403extending vertically from the top surface S401 to the bottom surfaceS402 and interconnected with thereof. In some embodiments, the entireside surface S403 of the heat dissipation block 400 is substantiallyflat. Since the depth H1 of the cavity C1 (shown in FIG. 15) is smallerthan the thickness H4 of the heat dissipation block 400, the heatdissipation block 400 is protruded from the opening 303′. That is, thetop surface S401 of the heat dissipation block 400 is above the topsurface S1 of the open substrate 203′.

In some embodiments, the heat dissipation block 400 has arectangular-shaped in top view, but is not limited thereto. The heatdissipation block 400 may have a length L1 parallel with the firstsidewall 310 and a length L2 perpendicular to the length L1. In someembodiments, the length L2 is slightly greater than the distance D2(shown in FIG. 18) between the first fixing portion 312 a′ and thesecond fixing portion 322 a′. The length L1 may be slightly greater thanthe distance D1 (shown in FIG. 18) between the third fixing portion 332a′ and the fourth fixing portion 342 a′. In some embodiments, a distancebetween the first sidewall 310 and the second sidewall 320 is greaterthan the width W5 of cavity C1 (shown in FIG. 15) which is greater thanthe length L2 of the heat dissipation block 400. Similarly, a distancebetween the third sidewall and the fourth sidewall may be greater than awidth of the cavity C1 parallel to the first sidewall 310 which isgreater than the length L1 of the heat dissipation block 400. In someembodiments, the width W5 of the cavity C1 is of about 1.03-1.1 of thelength L2 of the heat dissipation block 400.

In some embodiments, the heat dissipation block 400 includes a ceramicor composite material. For example, the entire heat dissipation block400 may be ceramic or composite material. The ceramic or compositematerial may have low coefficient of thermal expansion, which isrelatively close to the substrate, compared with heat dissipation block400 made of metal material. Therefore, structural defect due to mismatchof thermal expansion coefficient between the substrate body 210 and theheat dissipation block 400 can be avoided. In some embodiments, the heatdissipation block 400 is selected from one of the group consisting ofaluminum silicon carbide (AISiC), tungsten copper alloy (CuW), tungstenmolybdenum alloy (CuMo), silicon carbide (SiC), silicon nitride (AlN),beryllia, chemical vapor deposition diamond (CVD diamond), diamondpowder-doped copper, diamond powder-doped aluminum, carbon-basednano-aluminum composite material (CarbAl-N) and carbon-basednano-aluminum composite material (CarbAl-G). In some embodiments, CuWincludes 10-20% copper (Cu). In some embodiments, CuMo includes 15-20%molybdenum (Mo). In some embodiments, the heat dissipation block 400includes aluminum nitride, aluminum carbide, aluminum silicon carbide,or a combination thereof, but is not limited thereto. The heatdissipation block 400 may be other materials having a low coefficient ofthermal expansion (e.g., less than 10 ppm/K) and low ductility. In someembodiments, the heat dissipation block 400 may have a metal layer (notshown) formed using a sputtering and/or plating process on its upper andlower surfaces.

Reference is made to FIGS. 19-21. In the operation 26 of FIG. 12, theheat dissipation block 400 is inserted in the opening 303′ to clamp theheat dissipation block between the first fixing portion 312 a′ and thesecond fixing portion 322 a′. FIG. 20 and FIG. 21 are respectivelycross-sectional views taken along line A-A′ and line B-B′ of FIG. 19. Insome embodiments, the heat dissipation block 400 protruded from theopening 303′ is pressed from its top surface S401 (shown in FIG. 18),such that the heat dissipation block 400 is squeeze into the opening303′ between the first fixing portion 312 a′ and the second fixingportion 322 a′. Therefore, the heat dissipation block 400 is directlyfixed in the opening 303′ without using adhesive. As such, the circuitboard 1000′ is formed.

As shown in FIG. 19, the first protrusion 316′ of the first fixingportion 312 a′ and the second protrusion 326′ of the second fixingportion 322 a′ are in contact with the heat dissipation block 400. Insome embodiments, the heat dissipation block 400 may also be clampedbetween the third fixing portion 332 a′ and the fourth fixing portion342 a′. Similarly, the third protrusions 336′ of the third fixingportion 332 a′ and the fourth protrusions 346′ of the fourth fixingportion 342 a′ are in contact with the heat dissipation block 400.

As shown in FIG. 19, a first recess 314′ may be located between the twofirst protrusions 316′ and the heat dissipation block 400, and thesecond recess 324′ may be located between the two second protrusions326′ and the heat dissipation block 400. Similarly, the third recess334′ may be located between the two third protrusions 336′ and the heatdissipation block 400, and the fourth recess 344′ may be located betweenthe two fourth protrusions 346′ and the heat dissipation block 400. Afirst gap 350 may be formed between the heat dissipation block 400 andthe first sidewall 310 of the opening 303′, and a second gap 360 may beformed between the heat dissipation block 400 and the second sidewall320 of the opening 303′.

As shown in FIG. 19 and FIG. 21, a bottom portion of the heatdissipation block 400 is tight contact with the first fixing portion 312a′ and the second fixing portion 322 a′. The heat dissipation block 400is fixed in the opening 303′ by the length L2 of the heat dissipationblock 400 being slightly larger than the distance D2 (shown in FIG. 18)between the first fixing portion 312 a′ and the second fixing portion322 a′. Similarly, the heat dissipation block 400 may be fixed in theopening 303′ by the length L1 of the heat dissipation block 400 beingslightly larger than the distance D1 (shown in FIG. 18) between thethird fixing portion 332 a′ and the fourth fixing portion 342 a′. Inaddition, because of the height H2 of the first fixing portion 312 a′and the second fixing portion 322 a′ are smaller than that of the heatdissipation block 400, the damage of the heat dissipation block 400having low ductility and the open substrate 203′ can be avoid when theheat dissipation block 400 is inserted into the open substrate 203′.That is, the heat dissipation block 400 may be more easily to be pressedinto opening 303′ compared with the opening 303 shown in FIG. 5.

In some embodiments, apertures 370 may be formed between the sidewallS403 of the heat dissipation block 400 and a sidewall of the cavity C1.The apertures 370 is on the first fixing portion 312 a′ and the secondfixing portion 322 a′. In some embodiments, the apertures has a depth ofabout 0.2-0.5 of a thickness of the substrate body. In some embodiments,the thickness H4 of the heat dissipation block 400 is substantiallyequal to the thickness H3 of the substrate body 210. Specifically, thetop surface S401 and the bottom surface S402 of the heat dissipationblock 400 may be respectively level with a top surface S1 and a bottomsurface S2 of the substrate body 210. The working heat source generatedby the electronic components (not shown) on the circuit board may betransmitted to outside of the circuit board 1000′ through heatconduction characteristics of the heat dissipation block 400 to maintainworking performance of the electronic components and maintain theirlife.

In some embodiment, after the operation 26 is completed, the method 20may include other operations or steps. Reference is made to FIG. 22,which is a top view of a process stage after the operation 26 accordingto some embodiments of the present disclosure. In some embodiments, themethod 20 further includes filling a resin material 500 in the remainingopening 303′ (shown in FIG. 19). Specifically, the resin material 500 isfilled in the apertures 370, the first gap 350, the second gap 360, thefirst recess 314′, and the second recess 324′. In some embodiments, themethod 20 further includes filling the resin material 500 in the thirdrecess 334′ and the fourth recess 344′. As shown in FIG. 22, all of thespaces between the heat dissipation block 400 and the substrate body 210may be filled with the resin material 500, so that the heat dissipationblock 400 is fixed in the opening 303′ to facilitate subsequentprocesses performed on the circuit board 2000′. It is noted that fillingthe resin material 500 in the remaining opening 303′ is an optionaloperation that can help the heat dissipation block 400 more firmly fixedin the opening 303′.

FIG. 23 and FIG. 24 are respectively cross-sectional view taken alongline A-A′ and line B-B′ of FIG. 22. Reference is made to FIG. 23 andFIG. 24. In some embodiments, the circuit board 2000′ may be amulti-layered circuit board. For example, the substrate body 210includes a core plate 101, a first circuit layer 110, a second circuitlayer 120, a first dielectric layer 112, a second dielectric layer 122,a first conductive layer 114, and a second conductive layer 124. Itshould be understood that the structure of the substrate body 210 is notlimited to that shown in FIG. 23 and FIG. 24, and the substrate body 210may be any circuit board having a multilayered structure.

Reference is made to FIG. 25, which is a cross-sectional view takenalong line B-B′ of FIG. 22 following the FIG. 24. In some embodiments, athird dielectric layer 610 and a fourth dielectric layer 620 are furtherformed over the top surface S1 and the bottom surface S2 of thesubstrate body 210, respectively. A third conductive layer 710 isfurther formed over the third dielectric layer 610 and a fourthconductive layer 720 is further formed beneath the fourth dielectriclayer 620. As shown in FIG. 25, the third dielectric layer 610 and thefourth dielectric layer 620 may be prepregs or other dielectricmaterials having fluidity. The third dielectric layer 610 and the fourthdielectric layer 620 may be filled in the first recess 314′ and thesecond recess 324′. In some embodiments, the third dielectric layer 610and the fourth dielectric layer 620 may also fill in all of the spacesbetween the heat dissipation block 400 and the open substrate 203′ shownin FIG. 16, such as apertures 370, the first gap. 350, the second gap360, the third recess 334′, and the fourth recess 344′. In someembodiments, the third conductive layer 710 and the fourth conductivelayer 720 may be copper foils.

As described above, according to the embodiments of the presentdisclosure, the method of manufacturing the circuit board having theheat dissipation block is provided. The heat dissipation block can bedirectly fixed in the opening by the specific open substrate shape. Inspecific, the heat dissipation block can be directly clamp between thefixing portions with the specific structure of the open substratewithout using an additional adhesive layer on the bottom of thesubstrate body before inserting the heat dissipation block in theopening. Since the heat dissipation block has been fixed by the fixingportions of the open substrate, the position of the heat dissipationblock does not shift during the subsequent processes. Therefore,compared with conventional method, the method of the present disclosurecan avoid the problems of the offset heat dissipation block and airbubble residue generated by using adhesive layer to fix heat dissipationblock, and the heat dissipation quality of the circuit board may beimproved. In addition, the present disclosure use heat dissipation blockmade of ceramics or other composite materials which are different fromthe commonly used copper heat dissipation block, so that provide adiverse selection of the heat dissipation block material. The ceramicsor other composite materials have low processability, low thermalexpansion coefficient and good thermal conductivity, such thatstructural defect due to mismatch of thermal expansion coefficientbetween the circuit board and the heat dissipation block can be avoided.

The present disclosure has been disclosed in the above embodiments, andis not intended to limit the present disclosure, and it is obvious tothose skilled in the art that various alternations and modifications maybe made without departing from the spirit and scope of the presentdisclosure. The scope of the present disclosure is defined by the scopeof the appended claims.

What is claimed is:
 1. A circuit board, comprising: an open substrate,comprising: a substrate body having a top surface and a bottom surface;an opening in the substrate body, wherein the opening has a firstsidewall and a second sidewall opposite to the first sidewall; and atleast one first fixing portion and at least one second fixing portionextending from the substrate body toward the opening, wherein the firstfixing portion and the second fixing portion are respectively protrudedfrom the first sidewall and the second sidewall; and a heat dissipationblock directly clamped between the first fixing portion and the secondfixing portion, wherein the heat dissipation block includes ceramic or acomposite material.
 2. The circuit board of claim 1, wherein an apertureis on the first fixing portion and the second fixing portion and betweenthe open substrate and a top portion of the heat dissipation block, andthe first fixing portion and the second fixing portion respectively havea height that is smaller than a thickness of the open substrate.
 3. Thecircuit board of claim 2, wherein a bottom portion of the heatdissipation block is tight contact with the first fixing portion and thesecond fixing portion.
 4. The circuit board of claim 2, wherein theaperture has a depth of about 0.2-0.5 of a thickness of the substratebody.
 5. The circuit board of claim 1, wherein the top surface of thesubstrate body is level with a top surface of the heat dissipationblock.
 6. The circuit board of claim 1, wherein the first fixing portionhas a first width protruding from the first sidewall, and the secondfixing portion has a second width protruding from the second sidewall,wherein the first width and the second width are in a range of fromabout 0.05 mm to about 0.5 mm.
 7. The circuit board of claim 1, whereinthe first fixing portion has at least two first protrusions in contactwith the heat dissipation block and at least one first recess locatedbetween the first protrusions and the heat dissipation block, and thesecond fixing portion has at least two second protrusions in contactwith the heat dissipation block and at least one second recess locatedbetween the second protrusions and the heat dissipation block.
 8. Thecircuit board of claim 1, wherein the open substrate further includes atleast one third fixing portion and at least one fourth fixing portionextending from the substrate body toward the opening, and the heatdissipation block is clamped between the third fixing portion and thefourth fixing portion.
 9. The circuit board of claim 1, wherein theopening has round corners at both ends of the first sidewall and thesecond sidewall.
 10. The circuit board of claim 1, wherein the heatdissipation block is selected from one of the group consisting ofaluminum silicon carbide (AISiC), tungsten copper alloy (CuW), tungstenmolybdenum alloy (CuMo), silicon carbide (SiC), silicon nitride (AlN),beryllia, chemical vapor deposition diamond (CVD diamond), diamondpowder-doped copper, diamond powder-doped aluminum, carbon-basednano-aluminum composite material (CarbAl-N) and carbon-basednano-aluminum composite material (CarbAl-G).
 11. A method ofmanufacturing a circuit board, comprising: forming an open substrate,wherein the open substrate comprises; a substrate body having a topsurface and a bottom surface; an opening in the substrate body, whereinthe opening has a first sidewall and a second sidewall opposite to thefirst sidewall; and at least one first fixing portion and at least onesecond fixing portion extending from the substrate body toward theopening, wherein the first fixing portion and the second fixing portionare respectively protruded from the first sidewall and the secondsidewall; and inserting the heat dissipation block in the opening toclamp the heat dissipation block between the first fixing portion andthe second fixing portion, wherein the heat dissipation block includesthe heat dissipation block comprises a ceramic or a composite material.12. The method of claim 11, further comprising: recessing the firstfixing portion and the second fixing portion to form an cavity; andplacing a heat dissipation block in the cavity.
 13. The method of claim12, wherein the cavity has a width of about 1.03-1.1 of a length of theheat dissipation block.
 14. The method of claim 12, wherein the cavityhas a depth of about 0.2-0.5 of the thickness of the substrate body. 15.The method of claim 12, wherein the heat dissipation block is supportedby the first fixing portion and the second fixing portion when placingthe heat dissipation block in the cavity.
 16. The method of claim 14,wherein the heat dissipation block has a length that is greater than adistance between the first fixing portion and the second fixing portion.17. The method of claim 12, wherein a top surface of the heatdissipation block is protruded from the top surface of the substratebody when placing the heat dissipation block in the cavity.
 18. Themethod of claim 11, wherein inserting the heat dissipation block in theopening comprises pressing from a top surface of heat dissipation blockto squeeze the heat dissipation block into the opening between the firstfixing portion and the second fixing portion.
 19. The method of claim11, wherein the open substrate further includes at least one thirdfixing portion and at least one fourth fixing portion extending from thesubstrate body toward the opening, and the heat dissipation block isclamped between the third fixing portion and the fourth fixing portion.20. The method of claim 11, wherein the heat dissipation block isselected from one of the group consisting of aluminum silicon carbide(AISiC), tungsten copper alloy (CuW), tungsten molybdenum alloy (CuMo),silicon carbide (SiC), silicon nitride (AlN), beryllia, chemical vapordeposition diamond (CVD diamond), diamond powder-doped copper, diamondpowder-doped aluminum, carbon-based nano-aluminum composite material(CarbAl-N) and carbon-based nano-aluminum composite material (CarbAl-G).